1. Field of the Invention
The present invention relates generally to a mobile communication system and, more particularly, to a device and method for transmitting power control bit patterns to allow a mobile station to distinguish a transmit antenna in a mobile communication system that employs transmission diversity.
2. Description of the Related Art
Transmit antenna diversity techniques are generally characterized by three features: (1) a base station simultaneously sends common pilot signals to a mobile station wherein each common pilot signal uses a different spreading sequence in accordance with a particular transmit antenna at the base station (2) one user""s data signal is transmitted via only one antenna among the plurality of antennas; and (3) the mobile station must have some prior knowledge about the identity of the transmit antenna that the base station is currently using to transmit the user""s data to the mobile station. If the mobile station does not have such knowledge it must otherwise correctly estimate the identity of the transmit antenna.
With regard to the third feature, as previously stated, the mobile station must have some prior knowledge about the identity of the antenna currently used by the base station for data transmission, or otherwise be able to estimate the antenna""s identity by means of received signals from the base station. In either case, it is necessary for the base station to send to the mobile station supplementary information about the transmit antenna.
Conventionally, the method for sending supplementary information about the transmit antenna involves the use of user-specific pilot symbols at the base station. As is well known in the art, communication systems that use pilot signals may be generally divided into two classes: a first class whereby different pilot signals are used according to each user communicating with the base station, and a second class whereby a common pilot channel is shared by all users. The common pilot channel system cannot be used to send information about the transmit antenna, since it is shared by all users.
It is generally known that to perform reverse link power control, the base station, after puncturing a data signal, inserts a power control bit (PCB) in the punctured data signal and transmits the modified signal to the mobile station. The present invention discloses a method which exploits the existing PCB bit insertion method to provide additional information to the mobile station about the transmit antenna to facilitate the implementation of transmission antenna diversity.
It is, therefore, an object of the present invention to provide a device and method for generating a different PCB pattern according to a transmit antenna and communicating the generated PCB pattern in a mobile communication system employing the transmit antenna diversity technique.
To achieve the above object of the present invention, there is provided a device and an associated method for communicating data between a base station having at least two transmit antennas, and a mobile station having at least one receive antenna in a mobile communication system, the device includes: a transmitter at the base station, for inserting power control bit (PCB) patterns into the data and sending the data with the PCB patterns inserted therein, the PCB patterns indicating one transmit antenna being used to transmit the data; and a receiver at the mobile station, for receiving the data, detecting the PCB patterns from the received data and determining the one transmit antenna from the detected PCB patterns.